OK, go for it then. Get yourself a Raspberry Pi so you don't tie up your main computer 24x7 (its really cheap to run too at a couple of watts), and mine away. When you'r bored with mining (or you're just earning dust in about 6 months time), you've still got yourself a really cool linux box to play with 

Plenty of info on https://bitcointalk.org/index.php?board=14.0

And yes, they are overpriced for what you can expect to earn over their lifetime. 2.0BTC, wholesale, you purchase at 2.5BTC (or more in USD on ebay). Will probably only earn you 1.0BTC through mining, and worthless resale value at the end of life. Don't do it (unless you're mining just for fun).

The USB Erupters are just another gimmick that will end up in a large loss for people. Sure, they might be great right now, but with BFL finally starting to deliver, these erupters will be outphased before anybody can make their ROI.

If you want to try it, go for it, but I'm not.